Industrial processes may be controlled in part by electronic systems using sensors. Some factory automated processes may be critical and/or time-sensitive. Faulty sensor values must not be reported to the central controller to prevent upsetting these processes.
With process control systems, it is critical that all process data that is reported back to the central controller be valid. During a wire break event using conventional wire break detection systems, it is possible to send intermediate process data values since the wire break event is asynchronous to the internal circuitry for the module. A wire break event asynchronous to the timing of the internal circuit can cause intermediate data results, which do not trigger a wire break event in a conventional wire break detection circuit, to be logged even though they do not represent valid sensor data.
Methods used to determine sensor wire integrity may typically induce a stimulus that will force a value of the sensor input to an invalid state if the sensor wiring is not intact. In this case, it is not always possible to differentiate between an over/under voltage condition and a wire-break event. These conditions are not acceptable in some process control systems.